Animal and Plant Health Inspection Service | Veterinary Services | 1 

1. Disease Information

1.1 General Disease and Pathogen Information: Tropilaelaps mites (including T.

clareae, T. koenigerum, T. thaii and T. mercedesae) are ectoparasites of honey bee 

(Apis) species. Each Tropilaelaps species has a different geographic range, but they 

are all native to Asia. Tropilaelaps have expanded host use to include Apis mellifera

honey bees. T. clareae and T. mercedesae are the most threatening to A. mellifera

colonies. Due to this, and other reasons, the geographic ranges of these two species 

are expanding. The mites feed on bee larvae and pupae causing brood malformation, 

nutrient deprivation, and death of bees. Mites can transmit pathogenic honey bee viral 

diseases. Infestations subsequently lead to colony decline or absconding. Tropilaelaps

mites may co-occur with Varroa mites in A. mellifera colonies. Because a Tropilaelaps

infestation has not yet been detected in a honey bee hive in the United States, it is 

considered a Foreign Animal Disease (FAD). 

1.2 Clinical Signs: Clinical signs of Tropilaelaps infestation in a hive resemble those of 

other parasitic infestations (e.g., Varroosis), including weak adult bees with shrunken 

and deformed wings and legs, and/or deformed abdomens, bees crawling (rather than 

flying) near the entrance of a hive, reduced lifespan of adult bees, brood cappings with 

small holes where worker bees attempted to remove dead brood, spotty brood 

patterns or dead brood that may smell of decay, and overall colony decline. Mites may 

also be seen with the naked eye on adult bees or brood. Early signs of Tropilaelaps

infestation may go unnoticed, but due to the mites’ short lifecycle (about one week), 

mite population growth is rapid and quickly causes colony decline and high hive 

mortality. 

2. Laboratory Criteria

2.1 Agent Isolation and Identification: A “bump” test of a brood frame or sticky board

placement under hive frames, especially when combined with acaricide use, are 

successful methods to dislodge and collect mites. Mites may also be isolated by 

submerging a sample of bees in alcohol, soapy water or powdered sugar then 

straining out the bees and allowing the mites to be collected and counted. However, 

Tropilaelaps spend relatively little time on adult bees, and are predominantly found in 

brood cells, making it difficult to gauge the degree of infestation using the above 

methods. Uncapping both drone and worker brood to examine the brood for mites aids 

in detection and helps indicate the extent of an infestation. Tropilaelaps can be 

identified by morphological methods using microscopy. Young mites are whitish, while 

adult mites are reddish-brown, 0.6-1 mm in size and have a narrow, elongated shape. 

Tropilaelaps are fast-moving mites with relatively long legs. These traits help 

distinguish them from the Varroa destructor mite, which is rounder, has shorter legs 

and is slower moving. Mites should be collected and sent to a laboratory for full 

Case Definition

Tropilaelaps Infestation of Honey Bees

(Notifiable) December 2023
Animal and Plant Health Inspection Service | Veterinary Services | 2

identification. Any suspected Tropilaelaps specimens submitted to a laboratory should 

arrive dead (in 70% ethanol or having been stored overnight at -20o C). 

2.2 Agent Characterization: If available, laboratory identification of the mite may also 

involve a combination of polymerase chain reaction (PCR) and sequencing for 

molecular identification to differentiate between Tropilaelaps species and the many 

morphologically similar mites.

2.3 Serology: NA.

3. Case Definition and Reporting Criteria

3.1 Suspect Case: Clinical signs, history, or epidemiology consistent with Tropilaelaps

infestation in a susceptible honey bee hive.

3.2 Presumptive Positive Case: A hive from which Tropilaelaps mites have been 

identified at a non-designated laboratory.

3.3 Confirmed Positive Case: A hive from which Tropilaelaps mites have been identified 

at a laboratory designated by APHIS Plant Protection and Quarantine.

4. Reporting Criteria: Tropilaelaps is a U.S. notifiable condition that is reportable immediately 

under the APHIS National List of Reportable Animal Diseases (NLRAD).

4.1 NLRAD reporting in accordance with the NLRAD Standards for notifiable diseases; 

and by APHIS to the World Organisation for Animal Health (WOAH).